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NDJ averaged SST anomalies (in Kelvin) during the fall/winter preceding the initial emergence of the last four human influenza pandemics
| Pandemic (first identification) | NDJ Niño 3.0 index | NDJ Niño 3.4 index |
| 1918–1920 (March 1918) | −1.081 | −1.030 |
| 1957–1958 (February 1957) | −0.687 | −0.596 |
| 1968–1969 (July 1968) | −0.936 | −0.535 |
| 2009–2010 (March 2009) | −0.216 | −0.627 |
Average SST anomalies are shown for the Niño 3.0 (5°S–5°N, 150°–90°W) and 3.4 (5°S–5°N, 170°–120°W) regions.
